1. Field of the Invention
The present invention generally relates to a shift device for marine transmission, and more particularly relates to an improved shift device that has a shift member to move a transmission between at least two positions.
2. Description of Related Art
Marine drives such as, for example, outboard motors are disposed at a stern of an associated watercraft. The outboard motors incorporate a propulsion device that propels the watercraft. The propulsion device typically is a propeller. A transmission is incorporated to couple the propulsion device with a prime mover such as, for example, an engine that powers the propulsion device. A shift mechanism also is incorporated to move the transmission among forward, reverse and neutral positions that correspond to forward, reverse and neutral modes of the propulsion device, respectively. The propulsion device can propel the watercraft forwardly when the transmission is set in the forward position, while the propulsion device can propel the watercraft rearwardly when the transmission is set in the reverse position. The propulsion device usually does not propel the watercraft when the transmission is set in the neutral position because the propulsion device typically is disconnected from the prime mover in this position.
Typically, a remote controller that is placed in a cockpit of the watercraft remotely operates the shift mechanism. Due to being separately located from each other, a control lever of the remote controller can be connected to the shift mechanism through a mechanical cable. For example, U.S. Pat. Nos. 5,050,461, 5,051,102, 6,015,319, 6,098,591 and Japanese Patent Publication 7-17486 disclose a mechanical shift control system that operates between the remote controller and the shift mechanism.
Such a mechanical shift control system is durable and reliable; however, such a system also needs a relatively long cable that requires relatively large space and is burdensome to install and repair.
An electrical shift control system can replace the mechanical shift control system to actuate the shift mechanism. In one arrangement, the movement of the control lever of the remote controller is electrically sensed and is sent to a control device as a shift position command. The control device controls the actuator based upon the shift position command such that the shift mechanism moves the transmission in accordance with the movement of the control lever.
The electrical shift control system does not need the mechanical cable. However, if the electrical shift control system falls into an abnormal condition, it can be difficult to shift the transmission. Users of an outboard motor thus may prefer one system over the other and, thus, may want to change a mechanical shift control system to an electrical shift control system, or vice versa. In such an exchange, for example, the mechanical cable is replaced by a shift actuator or, conversely, the shift actuator is replaced by the mechanical cable. A need therefore exists for an improved shift device that can be easily changed to the mechanical shift control system from the electrical shift control system and vice versa.
Generally, marine drives such as the outboard motors can have very limited space for their internal components because of the compact size of the outboard motor. A shift actuator, however, is normally required to be placed at a location near the shift mechanism of the outboard motor. Another need thus exists for an improved shift device that can arrange the shift actuator in the limited space while generally preserving the compact size of the outboard motor.